Quick question here, although I need to do some more testing.
Does anyone have an issue passing DTS 5.1 audio from the display to their AVR via ARC or optical? I'm unable to get it to work, but I could have sworn it worked before I had to get a replacement display. I've tried several different videos streamed via Plex, but anything with DTS gets to the AVR as PCM 2.0 channel audio. I've tried messing with settings on the display and in Plex. I even tried casting some test DTS surround videos from an Android app, but same result. Any Dolby surround format works fine.
I played the same test files from my PC connected to the AVR through HDMI and optical, and they play as they should in surround. Due to this, I don't believe the AVR is at fault. I plan on doing more testing with another TV connected to the AVR, to see if it passes through ARC or optical.
Is DTS supposed to pass through on the Vizio? Or am I misremembering it working before the replacement?